While working with MongoDB and Node js I face an issue. I have created mu mobile_no unique in starting and after some time I realized that I don’t need my mobile_no to be unique. so I just go to my model and remove the unique: true property from my table schema and rebuild my app after. But strange the changes in schema did not reflect, I will still get the same error, mobile no must be unique. I have read my tutorial and found this code to Drop an existing index from mongo or mongoose using Model.